Method and apparatus for plasma control

ABSTRACT

The present invention provides a method for plasma control, in which an electric field is generated in the direction perpendicular to the surface of an object to be processed in plasma atmosphere generated in a processing chamber and another electric field is generated in the direction parallel to the surface, and the direction of ion or electron in plasma atmosphere is controlled by controlling the composite electric field composed of both the electric fields. The invention provides also an apparatus for plasma control provided with a perpendicular electric field generating means for generating an electric field in the direction perpendicular to the surface of the object, and a parallel electric field generating means for generating an electric field in the direction parallel to the surface of the object.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for plasma control and anapparatus for plasma control used in plasma CVD, plasma RIE, andsputtering.

2. Description of the Related Art

Plasma processing is categorized to various technologies such as plasmaCVD, plasma RIE, sputtering and ion plating, but any way in the allthese technologies an object to be processed is placed in a processingchamber and a type of plasma is generated, thus the object is subjectedto film forming or etching by the action of ion or electron.

FIGS. 1A and 1B are schematic diagrams for illustrating conventionalplasma processing equipments, FIG. 1A shows a parallel flat plate type,and FIG. 1B shows ECR type equipments.

The parallel flat plate type equipment comprises a processing chamber 1in which the object 4 to be processed such as wafer is placed, top andbottom electrodes 5 and 6 provided facing each other in the processingchamber 1, and a DC bias 2 and high frequency bias 3 for applyingvoltage on the bottom electrode 6.

For processing using the parallel flat plate type plasma processingequipment, a gas (not shown) is introduced in the processing chamber 1,and high frequency bias 3 of, for example, 13.56 MHz is applied togenerate plasma 7 in a space between the top electrode 5 and the bottomelectrode 6, and thus, for example, a film is formed on the surface ofthe object 4.

Plasma 7 in the processing chamber 1 is controlled by electric fieldperpendicular to the surface of the object 4 and flow of the gas tomaintain the plasma density uniform.

The ECR type plasma processing equipment shown in FIG. 1B comprises aprocessing chamber 11 in which the object 10 to be processed is placed,a wave guide 11a for feeding microwave into the processing chamber 11,and coils 12 for generating magnetic field.

For operating the ECR type plasma processing equipment, a gas isintroduced into the processing chamber 11 and microwave with a frequencyof, for example, 2.45 GHz is fed to cause discharging, and the rotationof electrons which are being rotated by applying magnetic field from theboils 12 resonates with the frequency of microwave to generates highperformance plasma 13.

The plasma 13 in the processing chamber 1 is controlled by prescribedbias and gas flow to process the object 10.

In any plasma processing equipment for proper processing, ion orelectron is controlled to be projected perpendicular to the surface ofthe object.

Therefore, the quality of processing in the direction perpendicular tothe surface of the object, for example, film thickness and etchingdepth, can be controlled, but the quality in the direction other thanperpendicular direction cannot be controlled, and these equipments arenot suitable for processing of the object with complex structure.

For example, when a taper is to be provided at a trench and a oxide filmwith desired thickness is to be formed on the inside surface of thetrench on a semiconductor element, a conventional plasma processingequipment cannot control such processing, this disadvantage of theconventional equipment has been a serious problem for processing objectswith complex structure.

SUMMARY OF THE INVENTION

It is the first object of the present invention to control the movementof ion or electron in plasma using electric field and magnetic field.

It is the second object of the present invention to providesemiconductor devices processed with ion or electron in plasma undercontrolled condition.

The present invention provides a method for plasma control forcontrolling ion or electron in plasma atmosphere in a processing chamberin which the object to be processed is placed, electric fields aregenerated in the directions not only perpendicular to the surface of theobject but also parallel to the surface of the object, and the directionof ion or electron in plasma is controlled based on the compositeelectric field.

The present invention provides a method for plasma control as describedin the above mentioned inventions, in which the electric field in theparallel direction to the surface of the object is generated byinverting the direction of magnetic field generated in the paralleldirection to the surface periodically.

The present invention provides a method for plasma control forcontrolling the direction of ion or electron in plasma atmospheregenerated in a processing chamber in which the object to be processed isplaced, in which electric field is generated in the perpendiculardirection to the surface of the object and another electric fieldgenerated in the direction parallel to the surface of the object isrotated by rotating a magnetic field which is generated in the directionparallel to the surface around an axis perpendicular to the surface tocontrol ion or electron in the plasma atmosphere based on the compositeelectric field composed of both directions.

The present invention provides a method for plasma control as describedin the above mentioned inventions, in which ion or electron in plasmaatmosphere is controlled by adjusting gas pressure introduced in theprocessing chamber.

The present invention provides a method for plasma control as describedin the above mentioned inventions, in which the electric field generatedin the direction parallel to the surface of the object in the processingchamber is controlled based on reactance and conductivity of theelectrode on which the object is to be placed in the processing chamber.

The present invention provides a method for plasma control as describedin the above mentioned inventions, in which the magnetic flux densityaround the surface of the object is controlled based on the movingperiod of the magnetic field generated in the direction parallel to thesurface of the object.

The present invention provides a method for plasma control in accordancewith the above mentioned inventions, in which the invention is appliedwhen plasma is used for plasma CVD, plasma is used for plasma RIE,plasma is used for sputtering, and plasma is used for ion-plating.

The present invention provides a method for plasma control as describedin the above mentioned invention, wherein the invention is applied whenplasma is used for flattening of the object and plasma is used forpolishing of the object.

The present invention provides an apparatus for plasma control forcontrolling ion or electron in plasma atmosphere generated in aprocessing chamber in which the object to be processed is placed,provided with a perpendicular electric field generating means forgenerating an electric field in the direction perpendicular to thesurface of the object and a parallel electric field generating means forgenerating an electric field in the direction parallel to the surface ofthe object.

The present invention provides an apparatus for plasma control asdescribed in the above mentioned invention, in which the parallelelectric field generating means comprises a pair of coils providedfacing each other outside the processing chamber with interposition ofthe object and an power supply means for feeding an AC current with acertain period to the pair of coils.

The present invention provides an apparatus for plasma control forcontrolling ion or electron in plasma atmosphere generated in aprocessing chamber in which the object to be processed is placed,provided with a perpendicular electric field generating means forgenerating an electric field in the direction perpendicular to thesurface of the object and a rotating magnetic field generating means forrotating a magnetic field generated in the direction parallel to thesurface of the object.

The present invention provides an apparatus for plasma control asdescribed in the above mentioned invention, in which the rotatingmagnetic field generating means comprises a coil wound around the objectand a polyphase power supply for feeding a current to the coil.

The present invention provides an apparatus for plasma control, in whichthe rotating magnetic field generating means comprises a ring shapedpermanent magnet for generating a magnetic field in the directionparallel to the surface of the object provided around the object and arotating mechanism for rotating the permanent magnet around the object.

The present invention provides an apparatus for plasma control inaccordance the above mentioned inventions, in which a magnetic ring isprovided around the electrode on which the object is to be placed in theprocessing chamber and around the object.

The present invention provides an apparatus for plasma control which isapplied to plasma CVD apparatus, plasma RIE apparatus, sputteringapparatus, and ion-plating apparatus.

The present invention provides an apparatus for plasma control which isapplied to a flattening apparatus for flattening processing of theobject with plasma and a polishing apparatus for polishing processing ofthe object with plasma.

In the method for plasma control in accordance with the presentinvention, an electric field in the direction perpendicular to thesurface of the object is generated and also another electric field inthe direction parallel to the surface is generated, and the compositeelectric field composed of the perpendicular electric field and parallelelectric field provides a force to ion or electron to move in desireddirection, thus the direction of ion or electron is controlled.

In the method for plasma control in accordance with the presentinvention, a magnetic field is generated in the direction parallel tothe surface of the object and the direction of the magnetic field isinverted to generate an induced electric field around the magneticfield.

The induced electric field generated as described above is utilized asan electric field parallel to the surface of the object.

In the method for plasma control in accordance with present invention,the magnetic field generated in the direction parallel to the surface ofthe object is rotated around an axis perpendicular to the surface.

The rotation of the magnetic field generates an induced electric fieldaround the magnetic field, and the induced electric field rotates alongthe surface of the object.

The moving direction of ion or electron in plasma atmosphere iscontrolled by the resultant force of the rotating induced electric fieldand the electric field in the direction perpendicular to the surface ofthe object.

In addition, by controlling gas pressure introduced into the processingchamber to control the force provided to ion or electron, the movingdirection and moving speed of ion or electron are controlled.

By controlling the electric field generated in the direction parallel tothe surface of the object based on reactance and conductivity of theelectrode on which the object is to be placed in the processing chamberand by controlling magnetic flux density around the surface of theobject based on the moving period of the magnetic field generated in thedirection parallel to the surface of the object, magnetic flux whichpasses the electrode are excluded outside, and the effect on magneticflux around the surface of the object is mitigated.

In the apparatus for plasma control in accordance with the presentinvention, the electric field in the direction perpendicular to thesurface of the object is generated with a perpendicular electric fieldgenerating means and the other electric field in the direction parallelto the surface of the object is generated with a parallel electric fieldgenerating means.

The composite electric field composed of both the directions therebycontrols the moving direction of ion or electron in plasma atmosphere.

By rotating a magnetic field generated in the direction parallel to thesurface of the object using a rotating magnetic field generating means,an induced electric field is generated surrounding the magnetic field.

The induced electric field rotates along the surface of the object withthe rotation of the magnetic field, and the composite electric fieldcomposed of the induced electric field and the electric field in theperpendicular direction provides a force to ion or electron in plasmaatmosphere to control the moving direction of ion or electron.

By providing a magnetic ring around the electrode on which the object isto be placed in the processing chamber and around the object, thepassing of magnetic flux through the object is prevented to suppress thecircuit damage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic diagrams of an apparatus for plasmacontrol in accordance with related art, FIG. 1A is a parallel platetype, and FIG. 1B is an ECR type.

FIG. 2 is a schematic diagram for illustrating the outline of a methodfor plasma control of the first embodiment in accordance with thepresent invention.

FIGS. 3A and 3B are schematic diagrams for illustrating a method forinducing a parallel electric field by inverting magnetic field.

FIGS. 4A and 4B are schematic diagrams for illustrating a method forinducing parallel electric field by rotating magnetic field.

FIGS. 5A and 5B show the relationship between magnetic field andelectric field, FIG. 5A shows the plasma side, and FIG. 5B shows thebottom electrode side.

FIGS. 6A and 6B are schematic diagrams for illustrating the relationshipbetween frequency and magnetic flux.

FIG. 7 is a perspective view for illustrating an apparatus for plasmacontrol utilizing inverting magnetic field of the second embodiment inaccordance with the present invention.

FIGS. 8A and 8B show the third embodiment in accordance with the presentinvention, and is a diagram for illustrating an apparatus for plasmacontrol utilizing rotating magnetic field.

FIGS. 9A and 9B show the fourth embodiment in accordance with thepresent invention, and are diagrams for illustrating an apparatus forplasma control utilizing rotating magnetic field.

FIGS. 10A to 10C show the fifth embodiment in accordance with thepresent invention which is provided with a magnetic ring, FIG. 10A is aperspective view, FIG. 10B is a cross sectional view, and FIG. 10C is adiagram for illustrating the flow of magnetic flux.

FIGS. 11A to 11C are cross sectional views for illustrating theprocessing on a trench of the sixth embodiment in accordance with thepresent invention.

FIGS. 12A and 12B are sectional views for illustrating an example offilm forming in the seventh embodiment in accordance with the presentinvention.

FIGS. 13A and 13B are sectional views for illustrating an example offlattening processing of the eighth embodiment in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the method for plasma control and the apparatus forplasma control in accordance with the present invention will bedescribed hereinafter in detail referring to the drawings.

FIG. 2 is a schematic diagram for illustrating a method for plasmacontrol of the first embodiment in accordance with the present inventionshowing an example of a parallel plate type apparatus for plasmacontrol.

The method for plasma control is a method for controlling the movingdirection of ion or electron in plasma atmosphere 27 generated in aspace between the top electrode 25 and the bottom electrode 26 providedin a processing chamber 21.

The moving direction of ion or electron in plasma atmosphere 27 iscontrolled by controlling the direction of composite electric field Eccomposed of a perpendicular electric field Ev in the directionperpendicular to the surface of the object 24 such as a wafer and aparallel electric field E_(H) generated in the parallel direction in theprocessing chamber 21.

The electric field Ev in the direction perpendicular to the surface ofthe object 24 comprises a plasma sheath electric field generatedinevitably on the surface of the object 24, a DC bias electric fieldgenerated by DC bias 22 applied on the bottom electrode 26, and a highfrequency bias electric field generated by a high frequency bias 23with, for example, frequency of 13.56 MHz.

The electric field E_(H) in the direction parallel to the surface of theobject 24 comprises an induced electric field obtained by movement of amagnetic field in the direction parallel to the surface of the object 24as described hereinafter.

In the present invention, the moving direction of ion or electron inplasma atmosphere 27 is controlled by using the resultant compositeelectric field Ec which is obtained by combining the electric field Evperpendicular to the surface of the object 24 and the parallel electricfield E_(H), that is by controlling the ratio of EV/E_(H) properly.

The response of CF₄ ⁺, which is used for plasma etching, to the electricfield frequency is described.

The force (F) which is exerted on a CF₄ ⁺ ion in an electric field isdetermined by the product of a charge (q) and electric field strength(E) as represented by the equation (1). Also, the force (F) exerted on aCF₄ ⁺ ion is the product of the molecular weight of CF₄ ⁺ ion (M) andacceleration (α).

    F=qE=Mα                                              (1)

From the equation (1), the moved distance (L) of an CF₄ ⁺ ion at time tis represented by the equation (2).

    L=(1/2)αt.sup.2 =(1/2)(qE/M)t.sup.2                  (2)

From the equation (2), the moved distance Lv of a CF₄ ⁺ ion in theperpendicular electric field is represented by the equation (3).

    Lv=(1/2)(qEv/M)t.sup.2                                     (3)

Accordingly, for example, under a condition of 13.56 MHz (a half periodtime t=0.5×13.56×10⁻⁶ (Sec)), and an electric field strength Ev=2×10³V/m, the moved distance (Lv) of CF₄ ⁺ ion in a perpendicular electricfield is calculated to be 1.49×10⁻⁶ m.

Herein for easy understanding of the calculation, for perpendicular biaselectric field, the sum of the plasma sheath electric field and DC biaselectric field is zero, and only high frequency bias electric field istaken into the calculation.

Similarly based on the equation (2), the moved distance L_(H) of a CF₄ ⁺ion in a parallel electric field is represented by the equation (4).

    L.sub.H =(1/2)(qE.sub.H /M)t.sup.2                         (4)

Accordingly, for example, under a condition of 800 Hz (a half periodtime t=0.5×800×10⁻² (sec)), and an electric field strength E_(H)=1.5×102 V/m, the moved distance L_(H) of the CF₄ ⁺ ion is calculated tobe 3.21×101 m.

It is understandable from the calculations that under the high frequencyelectric field condition such as 13.56 MHz a CF₄ ⁺ ion moves only thedistance of microns, but under the low frequency electric fieldcondition such as 800 Hz for the parallel electric field the CF₄ ⁺ ionmoves the distance of meters.

The reason is that the mass of the ion is larger than the mass of anelectron and the difference in the mass causes the more delayed responseunder the higher frequency condition.

Based on the above mentioned principle, for example, by providingparallel electric field E_(H) with variable strength and frequency inaddition to a high frequency perpendicular electric field Ev with afrequency of 13.56 MHz, a composite electric field Ec in a desireddirection in the range from perpendicular to parallel to the surface ofthe object 24 is generated.

According to the present invention, the composite electric field Ec isapplied to control the moving direction of ion or electron in plasmaatmosphere 27, and thus the composite electric field Ec allows ion orelectron to be directed in the desired direction to the surface of theobject 24.

Then, a method for generating an electric field E_(H) parallel to thesurface of object 24 is described herein under.

FIG. 3 is a schematic diagram for illustrating a method for inducing aparallel electric field by utilizing inverting magnetic field.

In this method, a magnetic field with a magnetic flux density B isgenerated in the direction parallel to the surface of the object 24 inplasma atmosphere 27, and the direction is inverted periodically asshown in FIG. 3A and FIG. 3B to generate an induced electric field Earound the magnetic field in the direction surrounding the magneticfield.

By inverting induced electric field E, the parallel electric field E_(H)on the surface of the object 24 is inverted periodically in thedirection right to left and left to right in the figure.

Therefore, the direction of composite electric field Ec (refer to FIG.2) composed of the electric field E_(H) and the perpendicular electricfield Ev (refer to FIG. 2) is inverted with a certain angle, and thusthe direction of ion or electron in plasma atmosphere 27 is controlled.

FIGS. 4A and 4B are schematic diagrams for illustrating a method forinducing a parallel electric field by utilizing rotating magnetic field.

In this method, a magnetic field with a magnetic flux density of B isgenerated in the direction parallel to the surface of the object 24 inplasma atmosphere 27 (refer to FIG. 4A), the magnetic field is rotatedaround an axis perpendicular to the surface of the object 24.

By rotation of the parallel magnetic field, a band induced electricfield E is generated in the direction surrounding the magnetic field,and the band induced electric field E rotates along the surface of theobject 24 with the rotation of the magnetic field.

On the surface of the object 24, the parallel electric field E_(H)rotates with the rotation of the magnetic field, a composite electricfield Ec (refer to FIG. 2) composed of the parallel electric field E_(H)and the perpendicular electric field Ev (refer to FIG. 2) rotates with acertain angle to the surface of the object 24.

Then, a method for plasma control for controlling a parallel electricfield E_(H) uniformly and in parallel on the surface of the object 24.

As described hereinbefore, in the present invention, the direction ofion or electron in plasma atmosphere 28 is controlled by a compositeelectric field Ec composed of a parallel electric field E_(H) andperpendicular electric field Ev on the surface of the object 24.

The passing of the magnetic field for generating the parallel electricfield E_(H) through the bottom electrode 26 on which the object 24 is tobe placed causes the induction of an electric field on the bottomelectrode side 26. The induced electric field induces a current, and thecurrent induces a magnetic field.

Therefore, the magnetic field on the surface of the object 24 is acomposite magnetic field composed of a magnetic field on the plasma side27 and a magnetic field on the bottom electrode side 26.

FIGS. 5A and 5B show the relationship between magnetic field andelectric field on the plasma side and the bottom electrode side.

In FIG. 5, the arrow 1 represents an initially applied magnetic field,the arrow 2 represents an induced electric field, the arrow 3 representsan induced current, the arrow 4 represents an induced magnetic field,the arrow 5 represents a final magnetic field, and the arrow 6represents the strength and direction of the final induced electricfield.

As shown in the figure, an induced electric field represented by thearrow 2 is generated in the direction perpendicular to the initiallyapplied magnetic field represented by the arrow 1. The induced currentgenerated due to the induced electric field generates a phase differencedue to reactance as shown with the arrow 3.

On the plasma side shown in FIG. 5A, a phase angle lag of the inducedcurrent, the arrow 3, from the arrow 1 of angle θp is generated, and onthe bottom electrode side shown in FIG. 5B, a phase angle lag of theinduced current, the arrow 3, from the arrow 1 of angle θe is generated.

The angle θe is far larger than the angle θp, depending on thedifference, the direction and strength of the induced magnetic fieldrepresented by the arrow 4 and final magnetic field represented by thearrow 5 are varied respectively. The induced current represented by thearrow 3 on the bottom electrode side is larger than that on the plasmaside because the conductivity of the bottom electrode side is largerthan that of the plasma side.

Therefore, the direction and strength of the final induced electricfield represented by the arrow 6 of the plasma side is different fromthat of the bottom electrode side.

In the present invention, by utilizing the difference in the directionand strength of the final induced electric field represented by thearrow 6 between the plasma side and the bottom electrode side, thedirection and strength of the final induced electric field on the plasmaside and the bottom electrode side is controlled based on reactance andconductivity of the bottom electrode 26, and thus the electric fieldE_(H) in direction parallel to the surface of the object 24, which is acomposite electric field composed of these induced electric fields, iscontrolled.

For example, the use of material for the bottom electrode 26 with ahigher conductivity results in the larger phase lag of the inducedcurrent represented by the arrow 3 shown in FIG. 5B, the effect on thefinal induced electric field on the plasma side represented by the arrow6 in FIG. 5A is reduced to control the electric field E_(H) in paralleland uniform.

In addition, by optimization of reactance and conductivity of the bottomelectrode 26, the electric field E_(H) (refer to FIG. 2) in thedirection parallel to the surface of the object 24 is controlled inparallel and uniform to control properly the composite electrode Ec.

Then, a method for plasma control utilizing the relationship betweenmagnetic flux density and the magnetic field change with time(frequency) generated in plasma atmosphere 27 is described hereinunderwith reference to FIGS. 6A and 6B.

FIG. 6 is a diagram for describing the relationship between magneticflux density and magnetic field change with time in plasma atmosphere27.

As described hereinbefore, in the present invention, a magnetic fieldwith a magnetic flux density B is generated in plasma atmosphere 27, andthe magnetic field is subjected to a change (inversion and rotation) togenerates an electric field E_(H) in the direction parallel to thesurface of the object 24, and thus the direction of ion or electron inplasma atmosphere 27 is controlled.

On the other hand, also on the bottom electrode side 26 a magnetic fieldwith a magnetic flux density B' is generated, thus on the surface of theobject 24 a composite electric field composed of the electric field onthe bottom electrode side 27 and the electric field on plasma side 27determines the parallel electric field E_(H).

In the present invention, by controlling the change with time(frequency) of the magnetic field generated in plasma atmosphere 27, themagnetic flux density generated on the bottom electrode side 26 andmagnetic flux density around the surface of the object 24 are controlledto control the parallel electric field E_(H).

For example, the larger time change of the magnetic field generated inplasma atmosphere 27 results in more reduced magnetic flux which passesthrough the bottom electrode 26 as shown in FIG. 6B. The magnetic fluxis excluded to the vicinity of the surface of the object 24, andmagnetic flux density near the surface becomes high (skin effect).

The higher magnetic flux density near the surface of the object 24results in the more reduced electric field generated on the bottomelectrode side 26 and the more parallel, uniform, and strengthenedelectric field on plasma side 27, namely electric field E_(H) generatedin the direction parallel to the surface of the object 24.

In short, by controlling the time change of magnetic field in plasmaatmosphere 27, the electric field E_(H) in the direction parallel to thesurface of the object 24 is controlled in parallel and uniformly andstrengthened to control properly the composite electric field Ec.

In the present invention, plasma controlled by the method for plasmacontrol described hereinbefore is used for plasma treatment processessuch as plasma CVD, plasma RIE, sputtering, and ion plating.

Thereby, the direction of ion or electron in plasma atmosphere 27, thatis, the direction of the processing such as film formation and etchingis controlled.

In the present invention the plasma is used for also flattening andpolishing of objects 24.

In this case, by generating a composite electric field Ec in thedirection parallel to the surface of the object 24, the flattening andpolishing are made possible.

In the method for plasma control in accordance with the presentinvention, the direction of ion or electron in plasma atmosphere 27 maybe controlled by controlling gas pressure introduced into the processingchamber 21 (refer to FIG. 2).

For example, in the case which gas is introduced in the directionperpendicular to the surface of the object 24, by increasing thepressure the speed of ion or electron in plasma atmosphere 27 in theperpendicular direction, namely energy, can be increased, thus themoving direction and moving speed of ion or electron is controlled bycontrolling the gas pressure.

Then, an apparatus for plasma control of the second embodiment inaccordance with the present invention for practical application of themethod for parallel electric field induction is described herein under.

FIG. 7 is a schematic diagram for illustrating an apparatus for plasmacontrol for practical application of the method for parallel electricfield induction utilizing inverting magnetic field.

The apparatus for plasma control comprises a pair of coils 31 providedfacing each other with interposition of the object 33 and a single phaseAC power supply 32 for feeding an AC current with a certain period tothe coils 31.

The pair of coils 31 is provided, for example, outside the processingchamber 21 (refer to FIG. 2), the coils are fed with an AC current witha frequency in a range from several 10 Hz to several kHz to generate amagnetic field with a magnetic flux density B in the direction parallelto the surface of the object 33.

By changing the current fed to the coils 31, the magnetic field in thedirection parallel to the surface of the object 33 is invertedperiodically, the inversion of the magnetic field causes the generationof an induced electric field E in the direction surrounding the magneticfield.

The direction of the induced electric field E is inverted correspondingto the period of current, and also the direction of parallel electricfield E_(H) is inverted periodically.

In this apparatus for plasma control, the parallel electric field E_(H)which is being inverted directionally and the perpendicular electricfield Ev (refer to FIG. 2) by the high frequency bias 23 (refer to FIG.2) are generated, and the composite electric field Ec thereof (refer toFIG. 2) controls the moving direction of ion or electron in plasmaatmosphere 27.

Thereby, the film forming and etching processing in a desired directionon the object 33 is made possible.

FIGS. 8A, 8B, 9A, and 9B are schematic diagrams for illustrating anapparatus for plasma control of the third and fourth embodiments inaccordance with the present invention for practical application of theparallel electric field induction method utilizing rotating magneticfield.

The apparatus for plasma control shown in FIGS. 8A and 8B is providedwith a rotating magnetic field generating means comprising a coil 44wound around the object 42 and a multi-phase AC power supply 45 forfeeding a multi-phase (for example three-phase) AC current to the coil44, and by feeding a multi-phase AC current to the coil 44, the pseudomagnetic field with a magnetic flux density B generated in the directionparallel to the surface of the object 42 is rotated.

For example, by selecting a frequency in a range from several 10 Hz toseveral kHz for the three-phase AC current, the magnetic field generatedon the object 42 rotates around an axis perpendicular to the surface ofthe object 42 with a rpm depending on the frequency of the AC current.

With the rotation of the magnetic field, a band induced electric fieldis generated surrounding the magnetic field, then the band inducedelectric field E also rotates.

On the surface of the object 42, the parallel electric field E_(H)rotates (refer to FIG. 4B), thus in the apparatus for plasma control thecomposite electrode Ec composed of the electric field E_(H) and theperpendicular electric field Ev by the high frequency bias 23 as shownin FIG. 2 can control the moving direction of ion or electron in plasmaatmosphere.

An apparatus for plasma control shown in FIGS. 9A and 9B is providedwith a rotating magnetic field generating means comprising a permanentmagnet ring 53 provided around the object 50 for generating a magneticfield with a magnetic flux density B in the direction parallel to thesurface of the object 50 and a rotating mechanism (not shown in thefigure) for rotating the permanent magnet 53 around the object 50.

The permanent magnet ring 53 is constituted with four linked magnetsections of, for example, M₁, M₂, M₃, and M₄, and the cross-sectionalshape of the magnet is streamlined so as not to disturb gas flow whenthe magnet is rotated.

In this apparatus for plasma control, by rotating the permanent magnetring 53 at, for example, several thousands rpm to several ten thousandrpm, the magnetic field from N-pole to S-pole is rotated around an axisperpendicular to the surface of the object.

The rotation of the magnetic field causes the generation of a bandinduced electric field E (refer to FIG. 4B) surrounding the magneticfield, and the band electric field E also rotates.

The rotation of the induced electric field E induces the rotation of theparallel electric field E_(H) on the surface of the object 50.

The apparatus for plasma control can control the moving direction of ionor electron in plasma atmosphere with a composite electric field Eccomposed of the electric field E_(H) and the perpendicular electricfield Ev by the high frequency bias 23 as shown in FIG. 2.

FIGS. 10A to 10C are schematic diagrams for illustrating an example ofan apparatus for plasma control of the fifth embodiment in accordancewith the present invention provided with the magnetic ring, in whichFIG. 10A is a perspective view, FIG. 10B is a sectional view, and FIG.10C is a view for illustrating the line of magnetic flux.

As shown in FIGS. 10A and 10B, the apparatus for plasma control isprovided with a magnetic ring 64 around the bottom electrode 62 on whichthe object 60 is to be placed and the object 60 to prevent magnetic fluxfrom passing through the object 60 such as wafer and prevent theelectronic circuit from being damaged.

As shown in FIG. 10C, the magnetic field with a magnetic flux density Bin the direction parallel to the surface of the object 60 passes so asto get out the way of the bottom electrode 62 and the object 60 becauseof the existence of the magnetic ring 64, and the magnetic flux does notaffect on the internal of the object 60.

Thereby, a needless current in the object 60 is suppressed and theformed electronic circuit is prevented from damaging.

The apparatus for plasma control shown in FIGS. 7 to 10C may be, forexample, a plasma CVD apparatus, plasma RIE apparatus, spatteringapparatus, or ion plating apparatus.

The apparatus for plasma control may be a flattening apparatus forflattening treatment of the object or polishing apparatus for polishingtreatment of the object.

An apparatus for plasma control of the present invention used as variousprocessing apparatus is provided with an adjusting means (not shown infigures) for adjusting strength ratio and frequency ratio of theelectric field Ev in the direction perpendicular to the surface of theobject to the electric field E_(H) in the parallel direction, and byusing the adjusting means (not shown in figures), the direction ofcomposite electric field Ec (refer to FIG. 2) composed of the electricfield Ev (refer to FIG. 2) and the electric field E_(H) is controlled tocontrol the processing direction to the object.

FIGS. 11A to 13B are cross-sectional views for illustrating processingexamples using the method for plasma control and the apparatus forplasma control of the sixth, seventh, and eighth embodiments inaccordance with the present invention.

FIG. 11 is a sectional view for illustrating a processing example of atrench.

For example, when a trench 70a is to be formed in the directionperpendicular to the surface of the object 70 as shown in FIG. 11A usinga plasma RIE apparatus applied with the present invention, a compositeelectric field Ec is generated in the direction perpendicular to thesurface of the object 70 (for example, the electric field Ev is 100% andthe electric field E_(H) is 0% in FIG. 2) to control the direction ofion or electron, and thus a trench 70a perpendicular to the surface ofthe object 70 is formed.

When tapers are to be formed at the opening of the trench 70a, acomposite electric field Ec is generated in the direction depending onan taper angle as shown in FIG. 11B (composite electric field Ec isgenerated by composing the electric field Ev and the electric fieldE_(H), shown in FIG. 2, in a certain ratio depending on the taper angleto control the direction of ion or electron, and thus the opening isetched in a form of taper with a desired angle.

In a different way as shown in FIG. 11C, a composite electric field Ecis generated in the direction slant to the surface of the object 70 fromthe beginning, and a trench 70a with taper on both whole sides isformed.

According to the present invention, by using the adjusting meansdescribed hereinbefore, etching processing for forming various shapes ispossible using the same apparatus.

FIGS. 12A and 12B are sectional views for illustrating an example ofdeposit processing.

As shown in FIG. 12A, when a upside deposit A is to be formed on the topsurface of the object 80, for example, a composite electric field Ec isgenerated in the direction perpendicular to the surface of the object 80using a plasma CVD apparatus applied with the present invention.

Thereby, a surface deposit A is formed on the top surface of the object80 and bottom surface of a trench 80a.

When a lateral deposit B is to be formed on the lateral sides of atrench 80a as shown in FIG. 12B, by adjusting ratio of the electricfield Ev (refer to FIG. 2) to the electric field E_(H) (refer to FIG. 2)using the adjusting means described hereinbefore, a composite electricfield Ec is generated in the direction slant to the surface of theobject, the slant composite electric field Ec allows ion or electron toact on the lateral sides of the trench 80a.

Thereby, a lateral deposit B is formed on the lateral sides of a trench80a, thus the whole surface of the object 80, namely the top surface andall inside surfaces of a trench, is covered with deposit such as oxidefilm.

This method is a remarkably effective method especially formanufacturing trench capacitors accurately with high yield.

Examples of trench 80a processing are described herein above, but thisinvention by no means limited to the examples, and the invention isapplied to the inside surface treatment of various types of hole such asvia holes and contact holes.

FIGS. 13A and 13B are sectional views for illustrating flatteningprocessing.

As shown in FIG. 13A, when an insulating layer 92 is formed on theobject 90 on which wiring 91 of metal such as aluminum are providedpreviously usually the surface of the insulating layer 92 is wavedbecause of the underlaid projections of metal wiring 91.

To flatten the surface, a composite electric field Ec is generated inthe direction parallel to the surface of the object 90 using aflattening apparatus having the adjusting means described hereinbeforeapplied with the present invention.

The composite electric field Ec forces ion or electron in plasmaatmosphere 27 (refer to FIG. 2) to move in the direction parallel to thesurface of the object 90, and high spots on the surface of theinsulating layer 93 are removed off, thus the flattening is possible asshown in FIG. 13B.

When the object 90 is to be polished, a composite electric field Ec isgenerated in the direction along the polishing plane to control themoving direction of ion or electron, thereby, the polishing is possiblesimilarly to the flattening in which high spots are removed off.

By combining above described etching, depositing, and flattening whichutilize plasma, other processing such as etch back are possible.

In detail, the three dimensional processing to the object 90 is possibleby controlling ion or electron in plasma atmosphere (refer to FIG. 2)utilizing a composite electric field Ec composed of the electric fieldEv (refer to FIG. 2) in the direction perpendicular to the surface ofthe object 90 and the electric field E_(H) (refer to FIG. 2) in theparallel direction.

The frequency and strength of electric field in the embodimentsdescribed hereinbefore are only for example, and this invention by nomeans limited by the embodiments.

The processing examples described in the embodiments are also for onlyexample, and the present invention can be applied to other processing tothe object.

As described hereinbefore, the method for plasma control and theapparatus for plasma control in accordance with the present inventionexhibit the following effects.

In the present invention, not only the electric field in the directionperpendicular to the surface of the object but also the electric fieldin the parallel direction are controlled in plasma atmosphere,therefore, the moving direction of ion or electron in plasma atmospherecan be controlled as desired by the composite electric field composed ofboth the electric fields.

The electric field in the direction parallel to the surface of theobject is controlled based on reactance and conductivity of an electrodeon which the object is to be placed, and the magnetic flux density nearthe surface of the object is controlled based on moving period of amagnetic field generated in the direction parallel to the surface of theobject, thereby, an induced electric field generated in the directionparallel to the surface of the object is controlled in parallel anduniformly and is strengthened, thus the moving direction of ion orelectron is controlled accurately.

In addition, the moving speed of ion or electron is controlled byadjusting gas pressure introduced for plasma generation.

By applying these techniques, processing of a trench (taper processing),processing on the inside surface of a trench, flattening of an object,and polishing of an object are possible.

The present invention provides an effective method and apparatus forminimization of semiconductor elements and structuring of threedimensional semiconductor elements.

What is claimed is;:
 1. A method for plasma control for controlling thedirection of ions or electrons in a plasma atmosphere generated in aprocessing chamber in which an object to be processed is placed,comprising the steps of:generating an electric field in the directionperpendicular to the surface of said object, and generating anotherelectric field in the direction parallel to said surface by rotating amagnetic field generated in the direction parallel to the said surfacearound an axis perpendicular to said surface and said parallel electricfield is rotated, and controlling the direction of said ions orelectrons by controlling the composite electric field composed of saidelectric fields in both the directions, wherein said electric fieldgenerated in the direction parallel to the surface of said object iscontrolled based on reactance and conductivity of said electrode onwhich said object is to be placed in said processing chamber.
 2. Amethod for plasma control for controlling the direction of ion orelectron in plasma atmosphere generated in a processing chamber in whichan object to be processed is placed, wherein an electric field isgenerated in the direction perpendicular to the surface of said objectand an electric field is generated in the direction parallel to saidsurface, and the moving direction of said ion or electron is controlledby controlling the composite electric field composed of said electricfields in both the directions, wherein said electric field generated inthe direction parallel to the surface of said object is controlled basedon reactance and conductivity of said electrode on which said object isto be placed in said processing chamber.